Diesel Engine Energy Balance Study Operating

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DIESEL ENGINE ENERGY BALANCE STUDY OPERATING ON DIESEL AND

BIODIESEL FUELS

A thesis presented to

the faculty of

the Russ College of Engineering and Technology of Ohio University

In partial fulfillment

of the requirements for degree

Masters of Science

Scott J. Wallace

June 2007


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This thesis titled

DIESEL ENGINE ENERGY BALANCE STUDY OPERATING ON DIESEL

AND BIODIESEL FUELS

by

SCOTT J. WALLACE

has been approved for

the Department of Mechanical Engineering

and the Russ College of Engineering and Technology by

_____________________________________

Gregory G. Kremer

Associate Professor of Mechanical Engineering

_____________________________________

Dennis Irwin

Dean, Russ College of Engineering and Technology


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Abstract

WALLACE, SCOTT J., M.S., June 2007, Mechanical Engineering

DIESEL ENGINE ENERGY BALANCE STUDY OPERATING ON DIESEL

AND BIODIESEL FUELS (149 pp.)

Director of thesis: Gregory G. Kremer

The use of alternative fuels addresses the issues of: reducing dependence on

unstable petroleum supplies, reducing harmful emissions, and using renewable

energy sources. This thesis focuses on a comparative energy balance on a four

cylinder turbocharged diesel engine operating on diesel and biodiesel fuels.

Steady-state tests were run to experimentally determine how input energy in the

form of fuel was appropriated throughout the engine. The transfer of energy was

measured for losses to the engine coolant and exhaust, usable power output, as

well as minor and unaccounted losses. The results showed that input energy

from biodiesel was distributed 37.4%, 31.1%, and 29.6% to the major areas of

coolant, exhaust, and power output, respectively. Similarly the input energy from

diesel was distributed 37.5%, 31.4%, and 29.2% to the major areas of coolant,

exhaust, and power output, respectively. It was concluded from an uncertainty

analysis that there was not a statistically significant difference in these results.

Future improvements to obtain distinguishable results are outlined.

Approved: ________________________________________________

Gregory G. Kremer

Associate Professor of Mechanical Engineering


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Table of Contents

Page

Abstract3

List of Tables...6

List of Figures..7

Chapter 1: Introduction..101.1) Purpose.......10

1.1A) Goals and Objectives.101.2) Context..... 13

1.2A) Diesel Engine Development..131.2B) Biodiesel Background....181.2C) Biodiesel Benefits..181.2D) Biodiesel Production..201.2E) Program Background21

1.3) Scope..231.3A) Preparation of Laboratory and Base TestApparatus...231.3B) Testing Platform Validation..251.3C) Overview...25

Chapter 2: Literature Review.272.1) Databases and Sources...272.2) Energy Balances of Internal Combustion Engines....28

2.2A) Alternative Fuel Energy Balance Studies and theirResults....292.2B) Efficiency Tests with Equipment Modifications..322.2C) Energy Balance Theory.342.2D) Measurement Techniques.....37

2.3) Heat Transfer.392.4) Performance of Biodiesel...412.5) Adding to the Body of Knowledge....42

Chapter 3: Experimental Apparatus...433.1) Engine Selection443.2) Coupling the Engine to the Dynamometer.463.3) Measurement Equipment...48

Chapter 4: Test Plan...594.1) Throttle Position.60


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4.2) Energy Balance Calculations.624.3) Test Details....64

4.4)

Safety.....65

Chapter 5: Results..675.1) Coolant and Air Temperatures...675.2) Explanation of Data Averaging.....695.3) Data Analysis.725.4) Engine Torque745.5) Fuel and Exhaust Temperatures.765.6) Energy Distributions..77

Chapter 6: Conclusions..85

6.1)

Test Condition Conclusions...856.2) Energy Distribution Conclusions...876.3) Conclusions Suggesting Improvements to the Test Procedure and

Apparatus...936.4) Achievement of Goals and Objectives...96

Chapter 7: Future Work...100

References....102

Appendix A: Dynamometer Information.105

Appendix B: Cummins Information....111

Appendix C: Fuel Information.119

Appendix D: Hand Calculations..120

Appendix E: SOP/SER127


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List of Tables

Page

Table 3.1: Measurements, equipment, locations, and resolution/accuracies.49

Table 5.1: Relative energy distribution values and uncertainties..83

Table 5.2: Energy distribution based on input energy...84


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List of Figures

Page

Figure 1.1 Schematic layout of diesel and gasoline engines.....15

Figure 1.2: Cummins 5.9L diesel engine and common rail fuel system16

Figure 1.3: Program hierarchy...22

Figure 2.1: Schematic layout of the experimental set-up..38

Figure 3.1: Testing apparatus.43

Figure 3.2: Drawing of engine, stand, and radiator combination..45

Figure 3.3: Mounting system.46

Figure 3.4: Machined flywheel with mounted driveshaft flange...47

Figure 3.5: Keyed and grooved shaft between couplings with caps..48

Figure 3.6: Laboratory environment..50

Figure 3.7: Data logging station50

Figure 3.8: Test apparatus accessories...51

Figure 3.9: Test apparatus..51

Figure 3.10: Measurement equipment placement..52

Figure 3.11: Measurement equipment placement (other side of engine)...53

Figure 3.12: Coolant flow meter53

Figure 3.13: Coolant in thermocouple...54

Figure 3.14: Engine oil thermocouple...54

Figure 3.15: Fuel return thermocouple..55

Figure 3.16: Air intake thermocouple....55


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Figure 3.17: Coolant out thermocouple.56

Figure 3.18: Exhaust thermocouple and gauges57

Figure 3.19: Scale readout and stopwatch.57

Figure 3.20: Fuel tank/digital scale58

Figure 4.1: Throttle position for No. 2 diesel fuel only.61

Figure 5.1: B100 temperatures (except fuel and exhaust) for 20 min. trial...67

Figure 5.2: B100 coolant in and out temperatures 0-20 min.....69

Figure 5.3: Coolant data for B100 and diesel fuel respectively 0-20 min.....70

Figure 5.4: Comparison of ambient air and coolant measurements for B100 0-20

min.71

Figure 5.5: B100 engine coolant (out and in) 12-18 min...72

Figure 5.6: B100 torque values as a function of time 0-20 min74

Figure 5.7: B100 torque as a function of time 12-18 min.75

Figure 5.8: Fuel supply, fuel return, and exhaust temperatures 12-18 min...76

Figure 5.9: Relative energy distribution-power, coolant, exhaust, fuel, and air 12-

18 min....78

Figure 5.10: Relative energy distribution of power, coolant, and exhaust 12-18

min.79

Figure 5.11: Relative energy distribution of power and exhaust 12-18 min.80

Figure 5.12: Relative energy distribution of power and exhaust 12-18 min (with

error bars)...81

Figure 5.13: Comparison of relative energy distribution between biodiesel and

diesel fuel...82


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Figure 6.1: Comparison of thesis results (top) to Canakci and Hosoz (2006)

results.90


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Chapter 1: Introduction

1.1) Purpose

The purpose of this thesis was to perform an energy balance or energy appropriation

study on a compression ignition or diesel engine. Understanding where the energy gets

transferred for different fuel sources sets a baseline for future testing. The specific fuel

sources included No. 2 diesel fuel and B100 which is 100 percent neat biodiesel. These

fuel sources met the American Society for Testing and Materials (ASTM) standards of

D975 and D6751 respectively (ASTM Standards 2004).

1.1A) Goals and Objectives

This energy balance study was an initial step for studying algal-based biofuels as an

alternative fuel source in the near future. This is the programs main objective and the

work in this thesis will make a contribution towards achieving the final goal. The thesis

objectives were to monitor the amount of energy going into the engine provided by the

fuel source and then measure the energy output and losses throughout the system. This

main focus was intended to do three things:

A) Aid in validating the diagnostic systems functionality

B) Find out how the energy was transferred through the system for different fuel

sources


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C) Use applicable heat transfer modes of conduction, convection, and radiation to

determine energy transferred and learn how to properly design a controlled

and instrumented energy management system

A) Validation:

It was very important to use the results of this energy balance study to aid in the

validation of the engine diagnostic testing system. This was critical because there was

not a testing apparatus previously developed or in use, so one had to be implemented for

the first time requiring validation. A diesel engine, along with all of its necessary

mechanical and electrical components, was connected to a dynamometer for this testing

to take place. This also involved properly mounting the engine to a test stand and

developing a coupling system to the dynamometer. There were many thermal, torsional,

vibrational, and other factors that had to be accounted for in the development of this

system. Once the system was in operation, the energy balance study helped to make sure

that the system was operating properly. If there were significant losses through certain

parts of the system (uncharacteristic of those of benchmarked systems), the energy

balance study would show this and help identify the cause. It is necessary to have a

validated engine diagnostic testing system to perform meaningful research because the

precision and accuracy of the research is dependent on properly calibrated, accurate

equipment. Since this testing system was required for the energy balance study to take

place, its development is considered a task or deliverable and only the portions pertinent

to the study at hand will be covered in detail in this document.


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B) Energy Transfer:

This energy balance study was specifically designed to be done with No. 2 diesel fuel and

B100. The reason for this is that No. 2 diesel fuel has been in the past and still is the

most common fuel source used in diesel engines. It was used as a baseline comparison

for all results obtained with B100. The main reason that biodiesel was chosen as the

second fuel to study is that its use is increasing due to its renewability, safety,

environmental impacts, financial incentives, similar performance to No. 2 diesel fuel, and

other factors that are discussed in greater detail throughout this thesis. Therefore it made

sense to study how each of these fuels perform in a compression ignition engine.

One goal for studying how each specific fuel transferred its energy throughout the system

was to help indirectly draw conclusions on performance, combustion, lubrication, or

other characteristics of one fuel source compared to the other. Biodiesel can be blended

with No. 2 diesel fuel in any concentration from 0 up to 100 percent by volume. A 100

percent blend or B100 was chosen for use in this study because it exhibited

characteristics furthest from that of No. 2 diesel fuel than any other biodiesel blend. This

was important because the energy appropriation for No. 2 diesel fuel and B100 was very

similar. Maximizing the measurable differences enabled the use of standard measuring

devices such as flow meters, thermocouples, etc.


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C) Transfer Modes:

Portions of the combusted fuels energy were transferred into thermal losses by one of the

heat transfer modes of conduction, convection, or radiation. Therefore, these needed to

be implemented in the design of the thermal management system to insure consistency in

testing and proper data collection. This involved the use of a data logger and

instrumentation. It was also important to have a brief understanding of these to help draw

conclusions on the reaction each fuel source had in the engine to suggest further studies

to perform. For these reasons part of the chapter 2 focused on the modes of heat transfer

and, specifically, how they are accounted for.

1.2) Context

In order to set the proper context for the this thesis, it is important to have a brief

discussion of the diesel engines development up to date, biodiesel background

information as well as the need for alternative fuels, and some of this programs

background information.

1.2A) Diesel Engine Development

The compression ignition engine was developed in 1892 by the German engineer, Dr.

Rudolf Diesel (Leduc 2007). It was developed for using a variety of fuel sources such as

coal dust or peanut oil and it was shown at the 1900 World Exhibition in Paris, France

(Leduc 2007). Here peanut oil was the chosen fuel for the demonstration. In the early

1900s, Dr. Diesel was making statements implying that the use of the diesel engine with


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renewable fuels would help stimulate agricultural markets and that the renewable oils

may someday be as valuable as petroleum and coal products (Leduc 2007). It seems that

day is fast approaching.

The standard diesel engine operates on the principal that air in the engine cylinder is

compressed to an extremely high pressure and temperature at which time the fuel is

injected into the combustion chamber causing ignition. This is different from a gasoline

engine which compresses both the air and fuel at the same time. Once the air and fuel is

compressed, the gasoline engine relies on a spark to ignite the mixture causing

combustion. The spark ignition or gasoline engines need for electrical ignition requires

the use of many components such as spark plugs, ignition coil, distributor, and a

carburetor. The mechanical nature of the diesel engines design makes it simpler, more

rugged, more versatile, and its higher compression ratio makes it more efficient than the

gasoline engine. It is because of these basic principles of the diesel engines design that

make it such a good candidate for a near term solution to our renewable energy needs.

Figure 1.1 shows a basic schematic of a diesel and gasoline engine, respectively.


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Figure 1.1: Schematic layout of diesel and gasoline engines, respectively (NMRI, 2008)

The traditional drawbacks of the diesel engine are their cold weather operation, noisiness,

pollution, and lack of power. However, with advancements in technology, almost all of

these issues have been resolved. The most significant improvements were due to

improvements to the fuel injection and air induction systems. Traditional diesel engines

used indirect injection (IDI) systems where the fuel would enter a prechamber and

partially combust there. Currently most diesel engines use direct injection (DI) systems

where the injector tip is directed straight into the cylinders combustion chamber. The

result of this improved design is a quieter, cleaner, and more powerful engine.

Improvements to injection pumps and fuel injectors including higher pressures, multiple

injections per stroke, and optimized spray patterns have improved combustion

efficiencies resulting in more power, quieter delivery, and lower emissions from more

complete combustion.


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Advancements in diesel engine air induction systems have really propelled their use into

a variety of applications. The use of turbo chargers takes advantage of otherwise wasted

exhaust gases to help deliver more intake air to the engines combustion chambers. The

force from hot exhaust gases entering the turbocharger spins a turbine connected to a

compressor. The compressed air is then supplied to the engine increasing power and

lowering emissions. Figure 1.2 shows the 2003 Cummins 5.9L diesel engine and its

common rail fuel system.

Figure 1.2: Cummins 5.9L diesel engine and common rail fuel system (Memmolo 2008)

With the addition of the common rail fuel system in 2003, Cummins was able to achieve

24% more power, 10% more torque, and a wider powerband over its 2002 engine series

(Memmolo 2008). Utilizing the common rail fuel systems high pressures and multiple

injections per combustion cycle, increased throttle response, reduced noise, and improved


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cold-start times were all achieved, as well as NOx and hyrodcarbon emissions reductions

of 25% over the 2002 series (Memmolo 2008). In 2007, Cummins was able to make this

engine series almost 50% quieter with 10% higher common rail fuel pressures as well as

other improvements (Cummins, Inc.). Additionally, This engine unilizes cooled exhaust

gas recirculation (EGR) and other air-handling concepts, including Cummins own

proprietary sliding-nozzle Variable Geometry Turbocharger to give optimum boost level

as a function of engine rpm and load. The multi-injection-capable fuel system is then

used to manage in-cylinder conditions to limit emissions. The particulate filter reduces

Particulate Matter (PM) levels by 90% of pre-2007 levels (Cummins, Inc.). These are

all real-world examples of advanced diesel technology and their resulting improvements.

Diesel engine technology is a significant industry today. There is a lot of research being

done to maximize efficiencies, power, durability, and meet stringent emissions standards.

The basics of the diesel engine have been explained but there are many specifics that

have not been covered. To learn more about the current technologies including the

designs of injectors, pumps, heads, valves, turbochargers, intercoolers, and much more

see some of the manufacturers websites including Cummins, Caterpillar, Detroit, John

Deere, Kubota, or others. Another very good source is the Engine Manufacturers

Association (EMA). They are an association committed to improving engine technology

as well as emissions controls both domestically and internationally. They provide the

latest publications, legislations, position statements and news reports about issues in


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engine development. Their website is http://www.enginemanufacturers.org (Accessed

May 2007).

1.2B) Biodiesel Background

Since the use of biodiesel was so important for this thesis it is important to have general

background information about it. Biodiesel is a renewable fuel source produced from

natural oils through a chemical process to meet the specifications set forth by ASTM

D6751 (ASTM Standards 2004). It is intended to be used in conjunction with or as a

replacement for petroleum diesel fuel with little or no modification to the engine.

1.2C) Biodiesel Benefits

There is increased interest in biodiesel because of positive environmental impacts, safety,

energy security, economic impacts, and financial incentives. Global warming and other

environmental issues are starting to take precedence in the outlook for the future.

Biodiesel has proven to be a viable option to help address the issue of global health. The

use of biodiesel instead of petroleum diesel fuel will significantly lower the emissions of

hydrocarbons, carbon monoxide, sulfur dioxide, and particulate matter. Nitrogen oxide

emissions are not fully understood but many studies have shown that they increase up to

as much as 10-15% which is the only increase of emissions and this is an area of intense

study for potential improvements. Biodiesel also decreases the health risks of

transporting, storing and handling the fuel. Biodiesel is classified as biodegradable, non-

toxic, and non-flammable (ASTM Standards 2004; Leduc 2007). These properties make


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it safe in the event of accidental contamination into the environment. Since it is

biodegradable, spills will not require as much attention making transportation easier.

Because it is non-toxic, water supply contamination or exposure to skin is not a problem.

The high flash point of biodiesel makes storage much safer because it will not catch on

fire as easily as petrol diesel fuel.

With the prices of petroleum reaching record highs and the instability of imported oil

increasing annually, it is clear that there is a need to utilize more renewable fuel sources.

Biodiesel may help sustain the U.S. economy while providing a higher level of energy

security. Since biodiesel takes advantage of animal fats and vegetable oils, increased use

has helped stimulate agricultural markets and created many jobs in biodiesel production.

Besides stimulating our economy by providing our own fuel, it decreases the need for

military protection over foreign oil supplies which has be a major political issue for

years. Biodiesel helps preserve natural resources and create jobs which have prompted

our government to offer financial incentives to those producing the fuel. The government

subsidizes the fuel based on the amount and type of biodiesel blended into the petrol

diesel fuel. This helps make the prices competitive in an aggressive market. For the

most up-to-date information regarding issues related to the need for biodiesel visit the

home of the National Biodiesel Board: http://www.biodiesel.org/ (Accessed May 2007).


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1.2D) Biodiesel Production

Biodiesel can be produced from one of many processes. Some of the most common are

transesterification, pyrolysis, and microemulsions (Jha, Sharma and Marwaha 2004). The

vast majority of production facilities use a base-catalyzed transesterification process

using virgin (unused) oil from a domestic feedstock such as soybeans, rapeseed, mustard

seed, peanut, sunflower, or other oil producing plants. Biodiesel can also be made from

waste (used) vegetable oils or animal fats, but biodiesel from algae oil has the potential to

become dominant in the near future. Algae are becoming a feedstock of interest due to

its ability to rapidly reproduce as well as its high oil content. Studies have shown that

algae may be one of the most feasible ways to produce the amount of oil necessary to

fulfill the US diesel fuel needs (Sheehan, et al. 1998). For these reasons, our programs

final goal is to be able to produce algal-based biodiesel through a transesterification

process and test it for performance and emissions characteristics.

In the tranesterification process, a fat or oil (triglyceride) is reacted with an alcohol

(usually methanol or ethanol) to form three esters and one glycerol. To speed up the

reaction an increase the yield, a catalyst (usually NaOH or KOH) is used. During the

reaction, the triglyceride is broken down and the alcohol combines with the esters and the

catalyst combines with the glycerin. When this reaction is complete the result is

complete separation of the methyl or ethyl ester (biodiesel) and the glycerin soap. The

glycerin soap settles to the bottom and is siphoned off for addition processing. The

biodiesel is also processed further to insure that there are no un-used reactants left over.


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This is usually done through a washing process and then a drying process insures no

water contamination.

These are the basics of transesterification biodiesel production. The process is very

sensitive to catalysts, water contamination, molar ratio of alcohol to triglyceride, time,

temperatures, and other factors. It is extremely important to know that the quality of the

biodiesel used will affect all aspects of the system it is used in from performance to

emissions to engine wear. For these reasons, purchasing biodiesel from a supplier that

meets the ASTM D 6751 standard, is critical to receive all the benefits biodiesel has to

offer. There is also a Quality Management Program referred to as BQ-9000 that insures

proper storage, sampling, testing, blending, shipping, distribution, and fuel management

practices (BQ-9000 The National Biodiesel Accreditation Commission 2007).

Purchasing fuel from a marketer in this program is highly recommended for any research

application. For in-depth information about proper biodiesel production, contact one of

the BQ-9000 (http://www.bq-9000.org/ May 2007) certified suppliers such as Peter

Cremer North America, LP (http://www.petercremerna.com/ May 2007).

1.2E) Program Background

Our biofuels program is in its first year of existence. Graduate student Dhruv Kohli

helped me with the deliverable of ordering components and setting up the general testing

apparatus. We both performed tests on the system. I did the energy balance study and

Dhruv did NOx emission testing. We are both under the direction of Dr. Greg Kremer,


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our advisor. There are two other graduate students working on algae production and

there are about five other faculty members in the areas of mechanical, civil, and chemical

engineering as well as a botany professor on the biofuels committee. This program is

funded by the Ohio Coal Research Center (OCRC) under the direction of Dr. David

Bayless who is also on the biofuels committee. Within the Russ College of Engineering,

the OCRC falls under the direction of the Institute for Sustainable Energy and

Environment (ISEE) headed by Mike Prudich. At the university level, everything falls

under CE3 which is Ohio Universitys Consortium for Energy, Economics and the

Environment. CE3 is a multidisciplinary organization that brings together Ohio

University's George V. Voinovich Center for Leadership and Public Affairs, the Russ

College of Engineering and the College of Arts and Sciences to explore ways to develop

safe, reliable, affordable and non-polluting sources of energy (Reed 2007). Figure 1.3

shows a visual representation of the program hierarchy just discussed.

Figure 1.3: Program hierarchy


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1.3) Scope

In order to perform the research for this thesis there were certain deliverables that were

necessary to complete through collaboration with the other team members. These, along

with the individual tasks necessary to accomplish the work of this thesis, will be briefly

discussed to show the scope of this project.

1.3A) Preparation of Laboratory and Base Test Apparatus

The main deliverables for this project were in the basic layout of the engine diagnostic

testing system. These deliverables were performed in collaboration with Dhruv Kohli

and occasionally other students or faculty. The first thing we did was make room in lab

for our testing equipment. This involved removing aspects of the previous electric

vehicle testing equipment such as part of the chassis dynamometer, scraping the old

electric test vehicle, and removing the external battery supplies. Next we acquired an

engine which was specked out for our particular needs and supplied by Cummins Inc. out

of Columbus, Ohio. This engine was part of a complete power unit included all electrical

and cooling systems. It was mounted on a stand and needed a battery and fuel tank to be

operational. To couple the engine to our dynamometer we used the services of a

driveline shop to make a short driveshaft which connected the flywheel of the power unit

to the input shaft on the dynamometer. In order to insure that the exhaust properly exited

the lab, 3 exhaust tubing was run approximately 50 into lower temperature flexible


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tubing which reached the exterior of the building. An exhaust back pressure gauge was

implemented and compared with factory specifications to insure that high exhaust

pressures did not affect the diesel engine.

After everything was set up, the system was calibrated and run so that we could begin to

focus on our respective research areas. To make sure the existing dynamometer was

operating properly, the engines power curve was compared to the manufacturers

supplied data. The data collected for our engine compared very well throughout the

operating range showing only slightly less torque at high speeds, likely due to the fact

that the manufacturer's data was for the engine operating without a mechanical cooling

fan and alternator. In all it took about 12 weeks to complete the basic engine diagnostic

testing system. With all of the purchases we had to make for equipment and

miscellaneous items, the total cost of the basic system was around $2000 which included

the engine power unit, the fuel and exhaust systems, the mounting and coupling

equipment, and other miscellaneous parts.

My personal research area involved the development of the thermal measuring and

control systems for the engines lubrication, coolant and exhaust systems. In addition to

this, I set up the system to control and monitor the air and fuel going into the engine.

This involved monitoring the air and fuels temperatures and flow rates. Finally I had to

monitor the environmental and atmospheric conditions to insure accuracy and


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repeatability of the experiments. All of these things will be discussed in greater detail in

chapter 3.

1.3B) Testing Platform Validation

The expectations for comparing the results in this thesis were to use the experimental

results obtained from testing and compare them to similar results found through the

literature search. This was done to help validate that the implemented measuring systems

were recording meaningful data. The other analysis of the results came from the theory

behind the energy balance. Through energy conservation, the legitimacy of the results

was determined based on how much of the energy was accounted for in the measuring

systems implemented. This was also able to be compared with results found in other

energy appropriation studies. The results of this research helped to validate and improve

the understanding of the engine diagnostic testing system. This system is intended to be

used in the research and testing of algal-based biodiesel. The conclusions that were made

in this thesis for soy based biodiesel were intended to serve as a starting point to

understand the effects of algal-based biodiesel.

1.3C) Overview

The first chapter of this thesis was intended to serve as an introduction to the rest of the

thesis by stating the goals, objectives, proper context, and scope. The second chapter is

the literature review where the current uses of energy balance studies will be shown as

well as the measurement techniques and equipment used. The third chapter will cover


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the details of the experimental apparatus. The fourth chapter discusses test, modeling,

and analysis plans. Chapter five shows the results of this thesis and chapter six talks

about the conclusions. Chapter seven is the future work that this thesis will help to

accomplish.


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Chapter 2: Literature Review

This literature review covers the databases and sources used for acquiring accurate

information used for this thesis. Characteristics of energy balances performed by others

on internal combustion engines will be covered in addition to the effects of specific heat

transfer modes. This section also includes a comparison of No. 2 diesel fuel and

biodiesel and an explanation of how the work in this thesis fits into the body of biodiesel

knowledge.

2.1) Databases and Sources

In order to insure that information used for this literature review was accurate and

accepted as scholarly work, the sources and databases searched were limited to certain

areas. Through Ohio Universitys library resources most of this information was found.

The Engineering and Technology portion of Info Tree (the universitys information

gateway) granted access to Compendex which is A worldwide database, beginning in

1969, that indexes scholarly literature for all engineering disciplines, as well as related

fields in science and management (Info Tree Ohio University Libraries, 2003). This

also granted access to INSPEC and Science Citation Index Expanded which both index

thousands of scholarly articles and journals from around the world. Other sources used

through Ohio Universitys library were Ohio Links electronic thesis and dissertation

center and Academic Search Primer which can be accessed through EBSCO Host

Research Databases. Examples of the key words used in search are: energy balance,


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energy appropriation, engine energy balance study, heat loss analysis, diesel engine,

biodiesel energy balance, thermal balance, heat transfer, heat loss etc. Once results were

returned, the abstracts were read to determine relevance and full versions were acquired

accordingly.

Some internet sources were used for gaining both general and specific information.

Some scholarly journals were found through Google Scholar (http://scholar.google.com/

May 2007), and for up-to-date information on biodiesel, the home of the National

Biodiesel Board (www.biodiesel.org May 2007) was used.

2.2) Energy Balances of Internal Combustion Engines

In order to better understand the operation of heat engines, people have been studying

energy transfer throughout history dating back to the 1820s with Sadi Carnots

thermodynamic model of the Carnot engine (Leduc 2007). Since then there have been

many energy studies done on different types of internal combustion engines varying in

both scale and application. This portion of the literature review will focus on the

purposes, methods, and results found for similar energy balance studies performed by

other researchers. The energy balance studies researched on internal combustion engines

used both spark ignition and compression ignition engines. They varied in power from

about 5 - 200 Hp and had 1- 6 cylinders. They were all four-stroke engines with both

naturally aspirated and turbo charged air-induction systems. These tests were also

performed under steady-state conditions. Tests with these characteristics were focused


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on because they involved similar equipment, procedures, and objectives to the work in

this thesis.

2.2A) Alternative Fuel Energy Balance Studies and their Results

There are many reasons to perform an energy balance study on an engine. The

knowledge of how the energy is lost will help in finding means to reduce the same to

improve the performance of the engine in terms of efficiency and power output (Kumar,

et al. 2004). This seems to be the main reason behind most energy studies performed on

engines. By improving the efficiency of the engine, the result is a higher percentage of

the fuels energy getting converted into power output. This is noticed as improved

performance. Although the goal of understanding engine operation to improve efficiency

is common, there are many different reasons an energy balance study helps to reach this

goal. Energy balance studies help characterize the impact a change has on the overall

system. Once the impact is identified by the energy balance, one can attempt to either

maximize or oppose its use due to the benefits and drawbacks. These changes include

variations in fuel, physical changes to engine design, or adjustments of engine settings.

A) Hydrogen Supplementation

With the increased interest in alternative fuels, variations in fuel sources have been a

recent interest. A thermal balance was done to investigate the effects of hydrogen

addition to the gasoline-air mixture on a four stroke SI engine (Yuksel and Ceviz 2003).

From this study they were able to conclude that hydrogen addition improved


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performance, significantly reduced heat loss to coolant and unaccounted losses (36 and

30% respectively), had little effect on exhaust losses, and was most efficiently used under

high loading conditions (Yuksel and Ceviz 2003).

B) Octane Ratings

Energy analyses can also be used for testing different grades of the same type of fuel.

One study performed an energy balance study on a four-cylinder SI engine using gasoline

with three different octane numbers (91, 93, and 95.3) to test various performance

parameters for each fuel (Sayin, et al. 2006). In this study it was found that the engine

was less efficient when using higher octane fuel than the designed engine rating,

increased thermal losses from high octane fuel were through the exhaust, and energetic

performance parameters increased with increasing engine speed due to a more

homogenous mixture and a boosted turbulence in the combustion chamber (Sayin, et al.

2006).

C) Biodiesel Blends

Perhaps the most pertinent journal to the work in this thesis was Energy and Exergy

Analysis of a Diesel Engine Fuelled with Various Biodiesels (Canakci and Hosoz 2006).

Here, a four-cylinder, turbo-charged diesel engine was studied to determine the heat

transfer rates and performance parameters during operation using No. 2 diesel, SME

(soybean oil methyl ester), YGME (yellow grease methyl ester), and 20% blends of the

two biodiesels (Canakci and Hosoz 2006). This study concluded that the brake specific


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fuel consumption (BSFC) is inversely proportional with the lower heating value of the

fuel resulting in a 12-13% increase in fuel consumption (Canakci and Hosoz 2006). It

was also concluded that the pure SME and YGME biodiesels yield approximately 1.6%

higher thermal efficiencies compared to No. 2 diesel fuel due to better combustion

characteristics from the oxygenated fuels (Canakci and Hosoz 2006). Overall, it was

found that biodiesels and their blends show almost the same energetic performance with

No. 2 diesel fuel in terms of the fuel energy input, brake thermal efficiency, combustion

efficiency, heat loss, and exhaust loss (Canakci and Hosoz 2006). The distribution of

energy from the use of pure biodiesel resulted in approximate differences in heat loss,

exhaust loss, and brake work of 2.3%, -2.9%, and 0.6% respectively when compared to

No. 2 diesel (Canakci and Hosoz 2006).

D) Ethanol Supplementation

The final journal found that studied the effects of energy balances based on fuel blends

was Thermal balance of a single cylinder diesel engine operating on alternative fuels

(Ajav, Singh and Bhattacharya 2000). Here blends of 5, 10, 15, and 20% ethanol-diesel

where tested and compared to 100% diesel fuel and fumigated ethanol was also compared

to diesel (Ajav, Singh and Bhattacharya 2000). From the data it was concluded that at a

5% significance level, only the 15 and 20% ethanol-diesel blends had a positive impact

(Ajav, Singh and Bhattacharya 2000). In general, this energy balance showed that as the

load on the engine increased, the percentage of useful work increased, while the other

losses decreased. At the initial stage, the increase was more pronounced than at the latter


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stages of the loading conditions. This trend is due to the fact that the engine attains

optimum operation at the latter stages of loading conditions, and as such, the differences

in useful work is minimal (Ajav, Singh and Bhattacharya 2000). Also, As the

percentage of ethanol in the ethanol-diesel blends increased, there was an increase in the

quantum of useful work done by the engine as compared to diesel fuel operation. This is

because of the cooling effect of ethanol as well as more efficient combustion as compared

to diesel. Since both the exhaust gas temperature as well as the lubricating oil

temperatures were lower in the case of ethanol-diesel blend operations, there was less

heat loss through theses channels, and as such, more useful work was available at the

engine crankshaft (Ajav, Singh and Bhattacharya 2000). These four different studies are

examples where the authors theories could not have been adequately supported without

the energy balance data to back up these claims.

2.2B) Efficiency Tests with Equipment Modifications

Energy balance studies have recently been used to test for increases in efficiency due to

engine design changes such as improved injectors, pumps, heads, valves, turbochargers,

intercoolers, and other advanced technologies (Engine Manufacturers Association 2002).

Another engine design development that thermal balances have helped to evaluate is the

Low Heat Rejection Engine (LHRE). The literature shows that there has been a lot of

research done on this topic. In general, the energy balance checks to see if an application

of ceramic material to parts of an engines combustion chamber, cylinder head, valves,

and pistons will decrease the amount of energy lost to the cooling system and therefore


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increase crankshaft work (Taymaz 2006). There are many different conclusions that have

been made about LHREs through energy balances and the findings vary considerably

based on engine configurations, test conditions, and analysis techniques (Jaichandar and

Tamilporai 2003).

The literature shows that energy balance studies are also done to optimize engine settings

or system settings. Depending on the application, it may be important to have an engine

run for long periods of time under a single loading condition. For this reason it is

important to understand what range the engine will operate most efficiently (Kopac and

Koturk 2005). The effectiveness of advanced fuel delivery and variations in engine

timing has been evaluated based on energy conversion principles (Experiment 3:

Performance of an Internal Combustion (I.C.) Engine 2004). An energy balance was

done to show how performance parameters and exhaust emissions were influenced by the

temperature of the engine coolant (Abdelghaffar, et al. 2002). The finding from this

study showed that the volumetric efficiency (rate of combustion of air) is significantly

affected by the coolant temperature (Abdelghaffar, et al. 2002). Therefore, increasing

coolant temperature decreases the mass flow rate of fuel consumption and the cooling

losses. As a result, the brake specific fuel consumption decreases and the brake thermal

efficiency increases (Abdelghaffar, et al. 2002).


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2.2C) Energy Balance Theory

The methods and techniques for performing the energy balances found in this literature

review all followed the same basic principles. Energy balance for a direct injection

diesel engine shows that about one-third of fuel energy input is lost to environment

through heat transfer, another third is wasted as exhaust heat and only one-third is

available as shaft work (Sharma and Jindal 1989). While the percentages vary between

engines, this seems to be the accepted rule of thumb. Stated more precisely, energy

enters the engine in the form of fuel and leaves as energy in the exhaust, cooling water,

brake power and heat transfer. Heat losses must be decreased to improve the engine

efficiency. Therefore, it is very important to know the fraction of the heat loss

mechanisms (Yuksel and Ceviz 2003). Aside from energy transfer to power output,

exhaust, and engine components/coolant, all of these energy balance studies find the

unaccounted for losses which is the remainder of what was not measured (found from

energy conservation). Depending on the loading conditions, the percentage of the

unaccounted for losses ranged between 1 and 23% (Kumar, et al. 2004; Taymaz 2006;

Ajav, Singh and Bhattacharya 2000).

The equations for calculating the energy transferred to the different areas of the diesel

engine in this thesis were all developed from a handout titled Energy Balances on

Internal Combustion Engines, dated August 1997. This handout was put together and

supplied by Dr. Jon Van Gerpen, professor and chair of the biological and agricultural


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engineering department at the University of Idaho-Moscow. The input energy going into

the engine, , was given by the equation:

(1)

Here, is the fuel mass flow rate and is the lower heating value or energy content

of the supplied fuel.

The brake power output, , was calculated with the following equation:

(2)

Here, is the brake torque of the engine and is the angular velocity of the engine

crankshaft.

The losses through the exhaust were determined by measuring the air and fuel flow rates,

making the assumption of complete combustion to determine exhaust gas constituents,

and determining the exhaust gas temperature. Using ideal gas behavior concepts and the

supplied chemical composition of the fuel, the energy losses through the exhaust can be

determined. Here the air/fuel (A/F) ratio is calculated on a molar basis:

.......(3)

Then the chemical reaction needs to be balanced (diesel shown):

.. 0.21 0.79 ...(4)

After solving for the unknown values of, the input energy transferred into the exhaust,

, is given by:

, .....(5)


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Here, represents the molar ratio of each exhaust component per unit of fuel based on

the balanced values. represents the enthalpy values for these exhaust components at

the exhaust gas temperature () and at an air temperature of 77F (,).

To measure the energy transferred through conduction of engine components, the losses

to the coolant, , are calculated by:

T, T, T, T,(6)

Here, and are the mass and volume flow rates of the engine coolant respectively.

is the specific heat of the coolant at the temperature half way between the

temperature of the coolant coming out and going into the engine T, and T,.

Likewise, is the density of the coolant half way between T, and T,.

Similarly, the input energy transferred to the fuel () and inlet air () is given by:

T, T,.(7)

and

T, T,F...(8)

respectively. The nomenclature for equations 7 and 8 follow that of equation 6 with the

exception that T,

is the actual temperature of the ambient air entering into the engine

and T,F is the temperature of air at 77F.


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2.2D) Measurement Techniques

The measurement methods and equipment were very similar for most of the energy

balance studies that were examined. In order to measure the brake power of the engines

dynamometers were used. Hydraulic brake dynamometers were used in most cases

examined, however, it should be noted that other dynamometers such as water brake, fan

brake, prony brake, eddy current, direct current, or electric motor/generator

dynamometers could have been used (Winther 1975). For measuring losses to the

exhaust, there are two prominent methods used. The first involves finding the mass flow

rate of the exhaust by direct measurement or from adding the air and fuel flow rates into

the engine (Taymaz 2006). Then maximum heat can be found from cooling the exhaust

to ambient temperature (Taymaz 2006). Another method used takes advantage of known

chemical formulas for the fuel, air and fuel flow rates, and exhaust gas temperatures to

calculate losses through a balanced chemical reaction (Kumar, et al. 2004; Sayin, et al.

2006). Calorimeters can also be used to determine the losses through the exhaust (Yuksel

and Ceviz 2003). There are some common assumptions that have to be made such as

complete combustion, no water vapor in combustion air, and ideal gas behavior (Kumar,

et al. 2004; Sayin, et al. 2006).

Heat loss to the engine coolant was usually measured by finding the difference in coolant

temperature at the engines inlet and outlet. However, one study measured the heat loss

to the cylinder liner directly by placing chromel-alumel thermocouples at four axial

locations and two radial depths around it (Kumar, et al. 2004). This allowed them to


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examine how the temperature was distributed through the liner which helped them

understand the combustion characteristics (Kumar, et al. 2004). This study also

estimated the frictional power loss by calculating the indicated power from P- (pressure

vs. crank angle) diagrams produced by a storage oscilloscope (Kumar, et al. 2004). Other

studies attempted to measure friction losses through the heat transferred to the lubricating

oil (Taymaz 2006). It should be noted that for almost all temperature measurements of

the exhaust gases, engine coolants, and lubricating oils, type-K thermocouples where the

measuring devices chosen. It should also be noted that all studies used a data acquisition

system to constantly record all measurements. Figure 2.1 shows a schematic layout

example of the experimental set up from Taymaz (2006).

Figure 2.1: Schematic layout of the experimental set-up (Taymaz 2006)


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Air flow rates were measured with either some kind of flow meter or by a pressure

change (manometer) in a flow element (Kumar, et al. 2004; Sayin, et al. 2006). Fuel flow

rates were measured with flow meters or else by measuring the volume of fuel consumed

and the specific time of consumption (Kumar, et al. 2004; Yuksel and Ceviz 2003). Most

engine speeds were measured with tachometers. All tests measurements were taken

under steady state conditions and some studies mentioned that a no load preconditioning

period was implemented into their procedures (Kumar, et al. 2004). All steady state tests

were performed one of two ways. Either a constant speed was maintained and the

loading was changed, or the dynamometer maintained a constant load on the engine and

measurements were recorded at different engine speeds (Kumar, et al. 2004; Sayin, et al.

2006).

One other technique for performing an energy balance on an engine is through a

computer simulated mathematical model. This form of analysis is common but is

generally used for transient testing and which is unnecessary for the research of this

thesis (Rakopoulos and Giakoumis 2006; Yuan, et al. 2005).

2.3) Heat Transfer

All of the heat transfer that takes place in an engine happens in the form of conduction,

convection, or radiation. The energy transfer takes place through many different

interactions within the engine but the area of particular interest is in the combustion

process. This has a significant impact on engine performance and emissions and may be


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better understood through an energy balance study. Many studies have been done to

characterize combustion processes successfully, however, in the area of emissions,

particularly with biodiesel, fundamental principles of the NOx increase are still unclear

(Yuan, et al. 2005). It is known that combustion is the process that produces NOx

emissions (Monyem, Van Gerpen and Canakci 2001). Therefore, the effects of ignition

delay, overall cylinder temperatures, injection timing, and combustion timing are all

being intensely studied (Yuan, et al. 2005; Monyem, Van Gerpen and Canakci 2001).

Increases in overall cylinder temperatures tend to increase NOx emissions in oxygen rich

conditions (Spliethoff, et al. 1996). It has been found through modeling that biodiesel

fuels have higher overall cylinder temperatures than diesel fuel (Yuan, et al. 2005). This

makes sense with the NOx increase; however, the literature also shows that the flame

temperature for biodiesel is slightly below that for diesel fuel. This indicates that flame

temperature changes alone cannot adequately explain the higher levels of NOx observed

with biodesel (Monyem, Van Gerpen and Canakci 2001). In this study the adiabatic

flame temperatures of biodiesel were consistently lower than that of diesel fuel

(Monyem, Van Gerpen and Canakci 2001). This leads to the question of what causes the

higher cylinder temperatures (and therefore increased NOx emissions) when using

biodiesel.

One theory on this issue is that biodiesel actually could have a higher actual flame

temperature than diesel fuel but, since biodiesel produces lower in-cylinder soot


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concentrations, diesel fuel combustions have more heat radiated away from soot particles

in the flame region (Cheng, Upanieks and Mueller 2006). Through thorough examination

it was concluded that differences in adiabatic flame temperature cannot be a cause of

higher NOx from biodiesel (Cheng, Upanieks and Mueller 2006). Instead they claim

that actual flame temperature is affected by radiative heat transfer and that radiative heat

transfer from in-cylinder soot particles may play an important role in limiting peak flame

temperatures and therefore NOx emissions. Although the correlation cannot be

interpreted definitively as an indication of causation, previous work has suggested that

soot radiative heater transfer can significantly affect flame temperature and NOx

formation (Cheng, Upanieks and Mueller 2006). This is an area that the energy balance

performed in this thesis could add validation and therefore add to the body of biodiesel

knowledge.

2.4) Performance of Biodiesel

In this thesis, the energy transfer rates through a diesel engine have been examined using

a 100% neat biodiesel fuel and No. 2 diesel fuel. Consequently, it is important to have

some background information on biodiesel as it compares to No. 2 diesel fuel. Refer to

the home of the National Biodiesel Board: http://www.biodiesel.org/ (Accessed May

2007) for information about the biodiesel performance parameters of: energy content,

fuel economy, lubricity, compatibility with engine components, and cold weather

applications. This information is located through the websites Fuel Fact Sheets link

located on the main page.


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2.5) Adding to the Body of Knowledge

Another way the work in this thesis adds to the overall body of knowledge for biofuel

testing is that it serves as a source of validation for our overall engine diagnostic testing

system. By understanding what variables affected the operating conditions of the engine,

an instrumented and justified testing platform was developed for the first time of this

programs existence. This thesis also established testing and safety procedures for others

to follow. This testing platform will be used for future work in performance and

emissions testing of algal-based biodiesel which is the programs overall goal.


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Chapter 3: Experimental Apparatus

Figure 3.1 shows the instrumented engine energy balance testing apparatus. The

considerations and details of this will be discussed in this chapter.

Figure 3.1: Testing apparatus

The testing apparatus for the work involved in this thesis was all located in Stocker

Centers 012 laboratory which had previously been used for electric vehicle testing. The

only existing equipment in the lab that was used for this thesis was a 250 kW (335 hp)

eddy-current dynamometer and its control system. This liquid-cooled dynamometer was

set up and operational at the time the lab space was acquired. This unit had previously

been integrated into a roller carriage for chassis dynamometer testing which needed to be

disconnected and partially removed to make room for coupling the diesel engine directly

to the dynamometer. The manufacturers data for the Digalog AE 250 dynamometer can

be found in Appendix A.

En ine

Dynamometer


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3.1) Engine Selection

The diesel engine selection was based on the available lab space, the compatibility with

the existing engine dynamometer system, fuel consumption rate, and budget. Due to the

dynamometers location in the room and utilized space of other lab projects, the whole

diesel power unit including mounting and coupling systems had to fit within a tight

footprint of 3x 6 putting a significant restriction on the size of the engine. The diesel

engine also had to fall within an acceptable power range for the dynamometer. The

concern was that the dynamometer system would not be able to accurately read and

control the torque applied to the engine at low levels. It was determined from the

manufacturers data that the load cell in dynamometer was very precise and accurate but

that the controller for the dynamometer was the limiting factor. There was insignificant

information on the controller so it was determined experimentally from the previous

electric vehicle tests that the engine would have to be over 10 bhp to get into the

controllers accuracy range. Fuel consumption rate was a factor in the engine selection

because the availability of algal based biodiesel is extremely limited. Since the other

student working on this project (Dhruv Kohli) was using an algal biodiesel blend, he

determined an acceptable fuel consumption rate which for most engines limited the

power output to less than 100 bhp. Budget was the final constraint and while specifics

where not discussed it was stressed that getting the best value possible was very

important.


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The final engine selection was a 60 bhp, four cylinder, turbo charged, rotary IDI power

unit supplied by Cummins Inc. It was chosen because it met all of the criteria mentioned.

Figure 3.2 shows a rear and side view of the engine, stand and radiator combination with

dimensions listed in inches supplied by Cummins, Inc.

Figure 3.2: Drawing of engine, stand, and radiator combination (Cummins, Inc.)

It came as a complete power unit so it was already mounted on a stand, it was complete

from the radiator to the flywheel, and it came with everything to be operational besides a

battery and fuel tank. The power units footprint was 2.25x3 which allowed for

additional mounting equipment and a coupling system. The compact unit fell in the

middle of the power range desired due to the turbo charger which also increased

efficiency helping meet the fuel consumption requirements. Best of all, the engine was


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broken in by Cummins Inc. and they gave us a significant discount. All of the

manufacturers data was supplied with the power unit and is located in Appendix B. This

information was used with the permission of the distributor that supplied the engine and

is only intended for use within this project at Ohio University.

3.2) Coupling the Engine to the Dynamometer

In order to couple the engine to the dynamometer, a shop recommended by Cummins Inc.

supplied a short (17) shaft with universal joints at each end. Due to angle restrictions of

the universal joints the power unit had to be raised up about 7. To do this, two 6 I-

beams were used to support the power unit. They were bolted to the floor with concrete

anchors. Between the I-beams and the power unit framework, additional spacers were

placed to get the final desired height. Figure 3.3 show the I-beams, concrete anchors, and

additional spacers.

Figure 3.3: Mounting system

SpacersI-beamsConcrete anchors


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Connecting the driveshaft to the engines flywheel involved machining the surface flat

and tapping mounting holes for the driveshaft flange. Figure 3.4 shows the flywheel and

the driveshaft flange bolted on via the tapped mounting holes.

Figure 3.4: Machined flywheel with mounted driveshaft flange

On the dynamometer end, an 8 long 1 diameter solid 1040 steel shaft with 3/8 cut

keyways connected the driveshaft and dynamometer couplings. This shaft also had snap-

ring groves added to it and caps which constrained the shaft from moving horizontally

inside the couplings. Figure 3.5 shows this arrangement.

Machined surfaceMounted flange


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Figure 3.5: Keyed and grooved shaft between couplings with caps

This completed the mounting and coupling of the diesel power unit to the dynamometer

which was an essential deliverable that needed to be completed before the remainder of

the energy balance measurement equipment could be implemented.

3.3) Measurement Equipment

Table 3.1 contains the specific measurements, the type of measuring equipment,

equipment locations on the test apparatus, and the equipment resolution or accuracy need

to perform the energy balance on the system.

Dynamometer

coupling

Driveshaftcoupling

1 diameter

keyed/groved shaft

Snap-ring caps


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Table 3.1: Measurements, equipment, locations, and resolution/accuracies

Measurement Symbol Equipment Location Accuracy/Resolution

Brake torque b Dynamometer Driveshaft 0.5 lb-ft

Engine speed Dynamometer Driveshaft 0.5 Rpm

Brake power Pb Dynamometer Driveshaft 0.5 Hp

Intake air temp. Ta,i Type-Kthermocouple

Turbo outlet 3.6F

Fuel in temp. Tf,i Type-Kthermocouple

Supply line 3.6F

Fuel out temp. Tf,o Type-Kthermocouple

Return line 3.6F

Coolant intemp.

Tc,i Type-Kthermocouple

Water pumpinlet

3.6F

Coolant outtemp.

Tc,o Type-Kthermocouple

Radiator inlet 3.6F

Fuel mass flowrate

f Scale andstopwatch

Fuel tank 0.01 lb and 1 sec.

Fuelcomposition

Cx Hx Ox Table N/A N/A

Fuel LHV LHV Table N/A 7%

Exhaust temp. Tex Type-Kthermocouple

Exhaustmanifold

3.6F

Lubricating oiltemp.

Toil Type-Kthermocouple

Oil pan 3.6F

Air mass flowrate

aM Mass air flowmeter

Air cleaneroutlet

2%

Coolantvolumetric flowrate

Flow meter Water pumpinlet

5%

Amb. Air temp. Ta,amb Type-Kthermocouple

Air cleanerinlet

3.6F

Note: Most measurements were recorded with a data logger.


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The laboratory environment is shown in Figure 3.6.

Figure 3.6: Laboratory environment

Figure 3.7 shows the computer used to log the data during testing, the 12 volt power

supply for the mass air flow sensor, the data logger, and the dynamometer controls and

readout.

Figure 3.7: Data logging station

Dynamometercontrols and data

logging equipment.

Cooling systemDynamometer

Engine andmeasurementequipment

12 V powersupply

Data logger

Dyno controllerand readout

Computer


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Figure 3.8 shows a closer look at the experimental set up.

Figure 3.8: Test apparatus accessories

Figure 3.9 shows the test apparatus from a different angle.

Figure 3.9: Test apparatus


Engine controlsRadiatorAux. cooling fan

ExhaustDriveshaft guard

Thermocouple

and MAF wires

Engine/mountingstand


Driveshaft guardExhaust


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The following series of pictures shows the actual placement of the measurement

equipment on the engine. Figure 3.10 shows the exhaust, coolant out, and ambient air

thermocouple locations as well at the mass air flow sensor location (as labeled in the

picture).

Figure 3.10: Measurement equipment placement

Figure 3.11 shows the other side of the engine. Pictured are the coolant in, fuel supply,

and oil thermocouple locations. It also shows the fuel tank on top of its scale, the mass

air flow sensor, and the coolant flow meter location.

Ambient AirMass Air Flow

Coolant outExhaust


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Figure 3.11: Measurement equipment placement (other side of engine)

Figure 3.12 shows the coolant flow meter. The coolant flow path was out the bottom of

the radiator, up through the flow meter, and into the water up.

Figure 3.12: Coolant flow meter

Mass air flow

Oil

Fuel tank/scale

Fuel supplyCoolant in

Coolant flow

Coolant

flow meter


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Figure 3.13 shows the thermocouple placement to measure the coolant going into the

engine. It is located just above the coolant flow meter shown in the previous figure.

Figure 3.13: Coolant in thermocouple

Figure 3.14 shows the thermocouple placement to measure the engines lubricating oil

temperature. This thermocouple was inserted in place of the oil dipstick.

Figure 3.14: Engine oil thermocouple

Coolant In

Oil


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Figure 3.15 shows the thermocouple placement to measure the temperature of the fuel

returning to the fuel tank from the injection pump.

Figure 3.15: Fuel return thermocouple

Figure 3.16 shows the thermocouple placement to measure the intake air temperature

flowing through the intake manifold.

Figure 3.16: Air intake thermocouple

Fuel return

Intake air


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Figure 3.17 shows the thermocouple placement to measure the temperature of the engine

coolant leaving the engine and flowing into the radiator.

Figure 3.17: Coolant out thermocouple

Figure 3.18 shows the thermocouple placement to measure the temperature of the exhaust

flowing through the exhaust manifold. Also shown are the turbochargers boost gauge

and the exhaust back-pressure gauge.

Coolant out


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Figure 3.18: Exhaust thermocouple and gauges

Figure 3.19 shows the electronic stopwatch and readout for the scale used to measure the

weight of the fuel.

Figure 3.19: Scale readout and stopwatch

Exhaust

Back pressureand boostgauges


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Figure 3.20 shows the fuel tank with the fuel supply thermocouple sitting on top of the

digital scale.

Figure 3.20: Fuel tank/digital scale


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Chapter 4: Test Plan

In this energy balance study, a direct comparison on the appropriation of energy was

made between No. 2 Diesel fuel and B100. In order to insure accuracy and repeatability

there were many monitored factors as shown in Table 3.1. With respect to the

environmental conditions in the lab, the ambient air temperature was the most difficult

condition to deal with due to the amount of heat given off by the engine in such a small

lab space. The laboratory lacked both adequate ventilation and a direct source of cool

outside air. For these reasons, the ambient air temperature in the room increased

significantly after the engine was running. To deal with this challenge, the test plan

specified running steady-state trials consecutively in an attempt to keep the air

temperature in the lab as consistent as possible. Air circulation fans were used to keep

the room temperature more consistent during testing. Prior to starting the first trial of a

series of tests, the engine was run through a preconditioning period to get the engine and

room up to a consistent temperature before each data collection trial was started. This

involved running the engine under a full load condition at 2800 RPM (peak power point)

for about 15 minutes. Energy was supplied to the system (or diesel engine power unit) by

means of the respective fuel sources (No. 2 diesel and B100).

The energy content or lower heating value (LHV) of each fuel source was reported by

Energy and Exergy Analysis of a Diesel Engine Fuelled with Various Biodiesels

(Canakci and Hosoz 2006). This along with all other fuel data, such as the chemical


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composition, can be found in Appendix C. It was determined through an uncertainty

analysis that due to the high uncertainty of the fuels energy content (7%), the energy

balance measurements needed to be analyzed based on a relative energy distribution

instead of a direct measurement corresponding to the fuels energy input. This meant that

regardless of the amount of energy inputted by the fuel, the amount of energy transferred

to different areas of the engine was directly measured and compared to the total amount

measured on a percentage basis. This allowed for a direct energy balance comparison

between diesel and biodiesel fuels. This also made the uncertainties of the results based

primarily on the accuracy of the measurement equipment. This is important because the

uncertainties for the measurements need to be small to distinguish statistically significant

differences in energy appropriation between the fuel sources.

An energy balance analysis based on the input energy from was still performed to get an

indication of how much of the total energy was accounted for by the measurement

system. However, these results had higher uncertainties due to the inability to measure

the energy content of samples from each fuel type.

4.1) Throttle Position

The trials for biodiesel (which had lower benchmarked values for LHV than No. 2 diesel)

were run at full throttle. This should have insured repeatable fuel (and therefore energy)

supplies to the engine. The No. 2 diesel fuel trials were run at a slightly lower throttle

position in an attempt to keep the same amount of energy entering the system for the 2


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fuel sources. The main reasons for keeping the energy input constant for both No. 2

diesel fuel and B100 was to minimize differences in energy appropriation from different

engine efficiency ranges and characteristics of combustion efficiency could be directly

compared between the different fuels. To approximate the correct throttle position that

should be used to keep the diesel energy input the same as the biodiesel energy input, the

torque output for the biodiesel, running at full throttle, was recorded. Then under the

same operating conditions, diesel fuel was run at full throttle and then slowly backed

down until the torque output equaled that of the recorded biodiesel full throttle torque

output. The gap between the throttle lever and its stop was then measured with a set of

feeler gauges as shown in Figure 4.1.

Figure 4.1: Throttle position for No. 2 diesel fuel only

The feeler gauge shim needed to achieve the same torque was found to be 0.045. With

the shim inserted next to the stop and the throttle lever tightened up against it, the same

throttle position for the diesel fuel trials could be insured.

Feeler gauges

Throttle lever

Throttle-stop


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The engine was run at these respective throttle positions for biodiesel and diesel fuel.

The engine was also run at an engine speed of 2800 RPM. According to the engines fuel

consumption curves located in Appendix B, this speed required the highest fuel flow rate

in the engines operating capabilities. This therefore inputted the most energy making it

easier to measure the distribution through the engine. The measurement equipment used

for determining fuel flow rate was a calibrated scale accurate to 0.01 lb and a hand-held

timer realistically accurate to a 1 second human response (see Figure 3.19).

4.2) Energy Balance Method

The specific equations used for the energy balance calculations in this thesis have all be

described in section 2.2C along with the rest of the energy balance theory information.

The energy converted into power output was measured by the dynamometer. The

dynamometer was used to keep the engine speed at the constant, fixed value. With the

recorded speed and its respective torque value, the brake power output was calculated.

The losses through the exhaust were determined by measuring the air and fuel flow rates,

making the assumption of complete combustion to determine exhaust gas constituents,

and determining the exhaust gas temperature. Using ideal gas behavior concepts and the

supplied chemical composition of the fuel, the energy losses through the exhaust were

determined.


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To measure the energy transferred through conduction of engine components, the engine

coolant (convection media) temperature was determined with thermocouples placed at the

inlet (Figure 3.13) and outlet (Figure 3.17) of the engines water pump. These positions

gave the largest change in temperature for calculating the heat rejected to the engine

coolant.

Energy transferred to the lubricating oil from friction of moving engine components were

also accounted for in the engine coolant. The reason for this is because the engine has an

external oil cooler that the engine coolant passes through to lift off the heat transferred to

the oil. The remainder of energy transfer that was not measured was grouped into the

unaccounted losses.

All of the calculations for this thesis were performed in the EngineCalc tab of

Biodiesel.xlsandDiesel.xlsfor biodiesel and diesel fuels, respectively. These were

developed in Microsoft Excel worksheets as part of this thesis and this engine analysis

program is included as a supplement to the thesis. By linking the proper data to a table in

EngineCalc, all of the calculations are solved based on the inputs and the predetermined

constants. EngineCalc was also used to predict the proper enthalpy values for the

corresponding exhaust temperatures and it was used to automatically balance the

chemical reactions for the different fuels. As EngineCalc solves the energy balance

equations, it performs a measurement uncertainty analysis for each area of energy

transfer. It also determines the total systems measurement uncertainty. EngineCalc was
http://biodiesel.xls/http://biodiesel.xls/http://diesel.xls/http://diesel.xls/http://diesel.xls/http://diesel.xls/http://biodiesel.xls/


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also used to determine the uncertainty sensitivity of the A/F ratio on the exhaust losses

because a direct uncertainty calculation was very complicated. All of the calculations for

energy transfer and measurement uncertainty performed in EngineCalc were verified with

hand calculations and are included in Appendix D.

4.3) Test Details

Six independent trials for each of the two fuel sources were conducted in an attempt to

obtain high accuracy and research quality results. The trials were staggered between fuel

sources to insure that no deposits from the fuel supply system or products of incomplete

combustion affected the results. The trials were all performed under the same steady-

state conditions and the preconditioning period was used if necessary to insure that

proper engine conditions were present at the beginning of each trial. The official start to

a trial was based on the time that the engines coolant temperature coming out of the

engine reached 180F. At this time, the weight of the fuel on the scale was zeroed and

the stopwatch was started. The data logger was set up to record the temperature

measurements and the mass air flow measurements at a rate of 1 measurement/second.

During each trial the values for the torque output and the time at which they changed

were manually recorded. The end of each trial was exactly 20 minutes from the start and

at this time the final weight of the fuel consumed was recorded. This 20 minute time

period was based on the capacity of the engines fuel tank. Upon completion of a trial the

engine was shut down and the fuel sources were changed in preparation for the next trial.


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The break between trials was kept at about 10 minutes so that the conditions in the room

would not take long to re-stabilize and if there was a longer break, the 15 minute engine

preconditioning period described earlier was followed. A detailed outline of the engine

operating procedures and fuel changing is described in the standard operating procedures

(SOP) located in Appendix E.

Steady-state tests were chosen because they allow many measurements to be taken under

similar conditions reducing the precision or random errors by averaging. Additionally,

the engine and dynamometer controls do not allow for transient tests to be performed

with a degree of reproducibility need for research. Based on the six trials for each fuel

source and the number of measurements taken during each trial, EngineCalc was used to

validate that the system was measuring all areas of energy transfer and reporting the level

of accuracy based on the measurement equipment uncertainty. The goal of the equipment

selection and the number of readings taken were to be able to achieve the final percentage

of total energy transferred throughout the system with power, coolant, and exhaust

uncertainties of 0.25%, 0.50%, and 0.50% respectively. These uncertainty values are

based the accuracy needed to distinguish between the differences in energy appropriation

based on the benchmarked values given by (Canakci and Hosoz 2006) in 2.2C.

4.4) Safety

Safety was one of the main concerns during the tests for this thesis. Since the engine was

being tested within the confined space of the laboratory, exhaust emissions were a major


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concern. To insure that the exhaust emissions did not leak into the lab, a solid steel

exhaust was run from the engine to the laboratory exit with all joints sealed by high

temperature tape. A hand-held gas analyzer was always present in the lab as well as a

wall-mounted carbon monoxide detector. Protection from rotating objects was addressed

by a driveshaft guard. Personal protection equipment such as gloves, safety glasses, and

ear protection was always provided and tests were only run with at least two people

present. The SOP and SER (failure modes and effects analysis) located in Appendix E

addresses these safety concerns.


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Chapter 5: Results

5.1) Coolant and Air Temperatures

Data was collected for the work in this thesis on a trial by trial basis. The data from all 6

trials of each fuel was sorted and combined to plot the results for the individual

measurements (i.e. temperatures of coolant in, coolant out, ambient air, etc.). An

example of this is Figure 5.1 which shows all of the temperature measurements (with the

exception of the fuel and exhaust temperatures) for the 6 trials of B100 plotted over the

20 minute trial time period.

Figure 5.1: B100 temperatures (except fuel and exhaust) for 20 min. trial

Ambient Air


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The goal of the test plan was to achieve steady-state test conditions during most of the

trial. The temperatures shown in Figure 5.1 suggest that most of the measurements taken

began to stabilize around the 5-10 minute mark. It is also shown that the measurements

follow the same trends which were determined to be the result of the ambient air

temperature (bottom data set) controlled by the environmental conditions outside the

testing laboratory. The dependence the measurements had on the ambient air temperature

will be shown in greater detail later in this section. The trends and measured values for

the diesel fuel trials were very similar to the biodiesel trials; therefore, the diesel fuel

plots are only shown in comparisons with biodiesel when needed. All temperature

measurements and the mass air flow measurements (not shown) were data logged at a

rate of 1 reading per second.

A closer examination of the individual measurements revealed that the values did not

reach a true steady state condition and that the values were not consistent from trial to

trial. Figure 5.2 shows a closer view of the engine coolant temperatures going in and out

of the engine.


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Figure 5.2: B100 coolant in and out temperatures 0-20 min.

Figure 5.2 shows that the temperature readings in most trials increased throughout but

approached steady-state conditions in the later half of the trials. Additionally, the overall

temperatures decreased in most cases as the number of trials progressed. The data in trial

4 falls out of place with the other trials and it shows an uncharacteristic drop in the last

two minutes of testing.

5.2) Explanation of Data Averaging

After examining all of the data recorded in the full 20 minute trials, it was determined

that the best way to analyze the results was to pick a time period based on the most

consistent trial-to-trial data that could be averaged together and given an uncertainty

based on a 95% confidence interval. It was reasonable to average the data together for


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each fuel source because the data for both followed the same trends. Figure 5.3 shows

the coolant data for B100 and diesel fuel respectively. They are shown on the same

scales.

Figure 5.3: Coolant data for B100 and diesel fuel respectively 0-20 min.

As shown in Figure 5.3, both fuel sources exhibit the same trend of decreasing

temperatures as the number of trials progressed. It is also shown that generally, the

measured temperature values and temperature change from trial to trial correlated well

between the two fuel sources. As mentioned earlier, it was discovered that these trends

can be attributed to the ambient air temperature on which they are dependent. Figure 5.4

shows the correlation between the ambient air trends and the coolant measurements for

Documents

Diesel Engine Energy Balance Study Operating